1. Field of the Invention
This invention relates to a battery-powered appliance. More specifically, this invention relates to an appliance in which a battery pack supplying the power may be removed from the appliance and plugged into a conventional AC wall receptacle for charging.
2. Description of the Prior Art
In the prior art there have been attempts to provide appliances such as electrical razors with removable battery packs which have been chargeable by plugging them into wall receptacles. An example is disclosed in Fleckenstein et al, U.S. Pat. No. 3,281,636 issued Oct. 25, 1963. One of the problems with earlier such appliances is that the attachment between the body of the appliance and the battery pack has been dependent on the frictional engagement of the electric contacts of the appliance and battery pack themselves so that over time and with wear, the securement of the two parts together has become loose and unreliable.
In U.S. Pat. No. 3,757,194 which issued Sept. 4, 1973 to Weber et al a battery-pack section was slid into its place in the appliance housing. This unit was not provided with separate sets of contacts for discharging into the appliance and for insertion into a wall plug for charging, however.
The more recent U.S. Pat. No. 4,084,123 which issued Apr. 11, 1978 to Lineback et al provides a battery charger having a single set of contacts which may be used both for charging and discharging into the appliance, but some such earlier units have required an expensive conversion switch and complicated circuitry.